A conventional charged particle beam inspection system in which a plurality of particle beams is directed onto an object is known from WO 2005/024881. The system is an electron microscope in which a plurality of primary electron beams are focused in parallel to form an array of primary electron beam spots on the object. Electrons generated by the primary electrons and emanating from respective primary electron beam spots are received by a charged particle imaging optics to form a corresponding array of electron beams which are supplied to an electron detection system having an array of detection elements such that each electron beam is incident on a separate detection element. Detection signals generated from the detection elements are indicative of properties of the object at those locations where the primary electron beam spots are formed.
By scanning the array of primary electron beam spots across the object, it is possible to obtain an electron microscopic image of the object. It is desirable to obtain images at a high resolution, uniform resolution and a high throughput.